Watch Kamen Rider Build: Special Event Full Movie Free Online 123Movies. This premium event featured appearances by the main cast of Kamen Rider Build, who conversed and share stories about the filming of the show that fans were not able to hear elsewhere. The event also included a stage show with an original Kamen Rider Build story created just for the event, complete with lights, sounds, and special effects. The event was be held on Friday, May 4, 2018, and Saturday, May 5, 2018, at the Grand Prince Hotel New Takanawa.